Recently, there has been developed a design aiding system in which technologies of knowledge engineering are applied to a design problem. In this system, for an object of design (product), a model is configured according to attributes stipulating an object of design (product) and constraints existing between the attributes. When a designer supplies the system with values of attributes conforming to specifications of the product, necessary constraints are activated to sequentially determine values of attributes not decided, thereby developing a design plan. For example, as described in the JP-A-2-126370, there are hierarchically arranged frames defining attributes required for a designing job and information items of attributes necessary to attain the values thereof, for example frames defining performance evaluation items such as a specific fuel consumption and a radius of rotation and a gear ratio necessary to obtain these items. Moreover, there are memorized a designing order related to the respective attributes, namely, a design procedure as well as calculation formulae for computing output attributes from input attributes. When a value of an attribute defined in a lowest hierarchic layer is inputted or altered, attributes in higher hierarchic layers related thereto are checked through the hierarchic structure so as to extract the attributes, thereby sequentially setting values thereto. Accordingly, even for an input and/or an alteration of some values of attributes in which all necessary input attribute items are not included, there is efficiently generated a design procedure, namely, a design procedure and/or a modification procedure of attributes to obtain a solution for design.
Moreover, there has been described in the JP-A-3-92972 a method of determining values of attributes of a plurality of apparatuses constituting an object of design and values of attributes of a layout of arranging the apparatuses by use of knowledge processing. In this method, using knowledge of constraints related to a contour and an arrangement of the design object, knowledge associated with an order of arranging the respective apparatuses, and knowledge of evaluation after arrangement, there is conducted a search for each of the apparatuses in an ascending order of arrangement for candidate positions satisfying constraints. After one of the plural candidate positions is selected, the selected candidate position is set as a constraint such that a search is made for the next apparatus in the arrangement order for candidate positions so as to select one of the candidate positions. If any candidate position is not found for the apparatus at an intermediate point, a backtracking operation is achieved to change the candidate position of the apparatus previously arranged and then a search is made with respect to the varied position for candidate positions of the subsequent apparatus. This flow is repeatedly accomplished, namely, a search is made for all solutions of the candidates of values of attributes to decide the positions of all apparatuses without any conflict, thereby attaining a design plan conforming to the specifications of requirements.
According to the prior art described in the JP-A-2-126370, in a stage where the design ordering operation related to the respective attributes is arranged in a hierarchic structure, attributes which can be inputted are required to be beforehand defined in the lowest layer of the hierarchic structure; furthermore, the constraints as the relational rules between the attributes are represented in a procedural manner in the form of, for example, calculation formulae to computer output attributes from input attributes, and the technology cannot be applied to design in which input attributes cannot be beforehand assumed. For example, in a case where a relationship (constraint) of A=B+.alpha. exists between an attribute A and an attribute B, for a plurality of requests such as "the attribute A is known in a certain case, and it is desired to attain the attribute B from the value thereof; and the attribute B is known in another case, and it is desired to attain the attribute A from the value thereof", it is impossible to simultaneously express relational rules B=A-.alpha. and A=B+.alpha.. Consequently, there cannot be generated a design procedure. That is, in this conventional technology, the relationships between the input attributes and the output attributes are fixed, and the technology is applicable only to a small-sized problem in which a design procedure is definitely defined. This leads to a problem that the technology cannot cope with a design job having various request patterns of which input attributes and output attributes cannot be assumed in advance.
Furthermore, in the conventional technology described in the JP-A-3-92972, after there are decided all values of attributes of a plurality of apparatuses configuring the design object, an attempt is made for each apparatus in the ascending order of arrangement to search for candidate positions for other apparatuses so as to decide values of attributes of the layout. In other words, since the selection of apparatuses and the problem of layout are separated from each other, even in a case where the layout cannot be determined because of values of attributes of apparatuses, the processing to obtain all solutions of the layout of candidate positions are entirely attempted such that only when the design plan cannot be finally obtained, the processing is returned for the first time to the selection of values of attributes of apparatuses. This causes a problem that a long period of time is required from when the backtracking of design is occurred to when a design plan satisfying the required specifications is attained.
In addition, when the structure or the like of the building in which apparatuses are installed is altered in a process of design operation, a change occurs in the data structure as a set of attributes and a set of constraints of the apparatuses and layout. The prior art however is attended with a problem that the method cannot cope with the occurrence of such a change in the data structure of the design object in the search process.
Moreover, for the contents of knowledge along the design procedure in the conventional method, since the layout order of the respective apparatuses is a fixed flow, only values of attributes can be decided according to the order, which leads to a problem that it is impossible to create a design procedure in which the order of arranging apparatus is determined according to the state of design.
Furthermore, since heuristic knowledge such as a method of solving a case of occurrence of conflict between values of attributes cannot be easily incorporated in the system, there arises a problem that when such a conflict occurs in a process of design operation, the user conducts again an input operation to repeatedly accomplish trial and error.
In addition, there exists a problem that in a case of absence of a design plan satisfying all constraints, there cannot be attained a substitutional design plan which possibly satisfies the required specifications.
Moreover, as for the layout, there is employed a method of searching for all solutions in which either one of candidate positions of each apparatus is selected to determine candidate positions of the subsequent apparatus depending on the selected candidate position. This consequently leads to a problem that an optimal design plan cannot be efficiently attained.
Furthermore, since the value of candidate of each attribute is selected in a value-by-value manner to determine a value of another attribute depending thereon, it is impossible to create at a time a plurality of candidate design plans of layout, and hence there exists a problem that the user cannot recognize the type of a design plan to be obtained as a candidate from the inputted values of attributes.
In addition, in a case where the values of all attributes are not determined even after the possible design operations are completely executed according to values of attributes first inputted as the required specifications, if values of some attributes are not additionally inputted, the processing is stopped and hence there cannot be attained a design plan. However, there is missing a method of indicating the user, to proceed the design, the values of attributes to be inputted, which leads to a problem that a trial-and-error operation is required.
It is therefore an object of the present invention of this application, which has been devised to remove the problems above, to provide a design aiding method in which a design procedure is automatically generated in association with various patterns required and which can guide the design procedure in a situation where judgement of the user is necessitated, for example, at an occurrence of a plurality of candidates of values of attributes and at an occurrence of conflicts between the values of attributes appearing in a process of design operation, thereby appropriately generating a design plan at a high speed.